The Concept of Kidney Biomarkers
Chronic Kidney Disease (CKD) is a major health problem due to the loss of kidney function over time. Kidney disease often has no symptoms in its early stages and can go undetected until it is advanced into fatal stages. An estimated 10% of the population worldwide is affected by a variant of kidney disease. The two main causes of CKD are high blood pressure and diabetes. The human kidney is a rather complex organ, made up of 1 million functional units called nephrons. These nephrons are responsible for filtering our blood to help eliminate waste products that are produced by the body. There have been numerous studies focused on this disease over the years but there remains a need for improved therapeutics and identification and/or prediction of patient outcomes. Biomarkers will give us the potential to transform the way we detect early stages of kidney damage as well as quantify nephrotoxicity to help develop nephrotoxic drugs for the market. At Enzo, we offer a variety of products to study the early stages of acute kidney injury or renal failure including antibodies, recombinant proteins and sensitive
ELISA kits.
Tools to Help Detect Acute Kidney Injury
A buildup of waste in the kidneys can cause sudden episodes of kidney failure called Acute Kidney Injury (AKI), the precursor to acute renal failure. The sudden loss of kidney function can be the result of illness, physical trauma, or nephrotoxic drugs. Luckily, AKI can be reversible with early testing and diagnosis. Studies have identified biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL), heme oxygenase-1 (HO-1) or kidney injury molecule-1 (KIM-1) with varied success as diagnostic or prognostic indicators of kidney injury, disease progression, or nephrotoxicity. KIM-1 is a 30KDa, a type 1 membrane protein with an ectodomain that contains immunoglobulin (Ig), highly O-glycosylated mucin subdomains, and multiple N-glycosylation sites. It is the most highly upregulated protein in the proximal tubule of the injured kidney. It exists in very low levels in normal kidneys but when the kidneys experience injury, it is detectable in urine within 6 hours of injury. KIM-1 may be a biomarker for renal injury, which is significant in identifying kidney diseases and acute kidney injury. Enzo provides a comprehensive
KIM-1 (Human) ELISA Kit with a colorimetric and immunometric immunoassay kit for the quantitative determination of human KIM-1 in urine with results in less than 2 hours.
Figure 1: Rapidly quantify KIM-1, an Early Biomarker of AKI. Parallelism analysis using the KIM-1 (human) ELISA Kit (ADI-900-226) indicates antigen binding characteristics are similar to native KIM-1 in urine samples with no matrix interference at the dilutions tested.
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Figure 2: A typical calibration curve for NGAL (human) ELISA kit (BPD-KIT-036).
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NGAL (also known as Lipocalin-2 or Neutrophil Gelatinase-associated Lipocalin) is a small, ~25kDa secreted protein expressed in epithelial tissues and released into both urine and blood upon kidney tubular damage. The protein is protease resistant and over-expressed during inflammation, infection and certain cancers. During acute renal failure (ARF) caused by either ischemia or nephrotoxicity, NGAL is secreted in high levels into blood and urine within 2 hours or less of injury to the kidney. NGAL is also released at the time of acute kidney injury (AKI) unlike serum creatinine, another kidney diagnostic biomarker which may not be seen until 72 hours after injury when up to 50% of renal function may have already been lost. Drug-induced acute kidney injury accounts for as much as 25% of all episodes of acute renal failure - a serious problem in clinical medicine as well as in the pharmaceutical industry. In drug development, some therapeutic candidates fail due to unexpected toxic effects in the kidneys, resulting in adverse outcomes and ultimately development termination of these candidates (attrition). NGAL provides an excellent endogenous biomarker for acute kidney injury (AKI) which occurs prior to ARF. Changes in NGAL urine and blood can be used to assess kidney status as a supplement to other established medical products or procedures. Versatile BIOPORTO® NGAL ELISA kits can be used for detection of NGAL in a variety of species and sample types including human, dog, monkey, mouse, and pig.
Our
Creatinine Colorimetric Detection Kit is a complete kit for the quantitative determination of creatinine in urine. Creatinine (2-amino-1-methyl-5H-imadazol-4-one) is a metabolite of phosphocreatine (p-creatine), a molecule used as a store for high-energy phosphate that can be utilized by tissues for the production of ATP. Creatine either comes from the diet or is synthesized from the amino acids arginine, glycine, and methionine. This occurs in the kidneys and liver, although other organ systems may be involved and species-specific differences may exist. Creatine and p-creatine are converted non-enzymatically to the metabolite creatinine, which diffuses into the blood and is excreted by the kidneys. Creatinine forms spontaneously from p-creatine, and under normal conditions, its formation occurs at a relatively constant rate. Intra-individual variation of creatinine levels is <15% from day to day, making it a useful marker for normalizing levels of other molecules found in urine. Altered creatinine levels may be associated with conditions that result in decreased renal blood flow, such as diabetes and cardiovascular disease.
Figure 3: Creatine and phosphocreatine are spontaneously converted to creatinine.
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Tools to Detect Chronic Kidney Disease (CDK)
CDK is a long and steadily slow process where the kidneys lose their ability to function. If not resolved, Chronic Kidney Disease can progress to End Stage Renal Disease (ESRD). During ESRD, the kidneys are no longer able to remove sufficient waste and excess fluid from the body, requiring the need for dialysis or a kidney transplant. Numerous studies have identified a number of proteins and metabolites present in blood or urine with diagnostic or prognostic markers of these various stages of kidney injury, disease progression, or nephrotoxicity. One of these markers is Cystatin C, which is a major member of a large family of endogenous cysteine protease inhibitors found throughout our body. Cystatin C is largely produced and filtered from the glomerular membrane, then completely reabsorbed from the proximal tubular cells. Cystatin C is a biomarker that has the ability to estimate GFR and kidney functions in serum, plasma, and urine. We offer
Cystatin C isolated from human urine that can be used for the inhibition of cysteine protease activity.
The biomarkers in AKI and CKD share similarities as both diseases exhibit a reduction in nephron numbers, vascular insufficiency, and cell cycle disruption. NGAL, KIM-1 and Cystatin-C biomarkers are present in both diseases, meaning there is an increased importance on utilizing kits to detect early. With the use of biomarkers it can hopefully shed some light in facilitating early diagnosis, guiding target intervention and monitoring disease progression and resolution. At Enzo, we provide a wide range of products for all your detection for kidney injury and nephrotoxicity research needs. Our platform provides a wide range of small molecules, antibodies, proteins, and ELISA that provides a variety of tools to detect the early stages of acute kidney injury. Including our flagship
SCREEN-WELL® Nephrotoxicity Library which contains 86 focused compounds with defined and diverse nephrotoxicity. Feel free to check out our
Successful Research Tips. Additional, contact our
Technical Support Team for further assistance.
